Samvariation mellan systematiska räkningar och spontan rapportering av rastande vadare i Getteröns naturreservat

Abstract

This paper is an attempt to describe how strong the covariation is between systematic counts and spontaneous reporting of staging waders at the Getterön Nature Reserve in southwestern Sweden. The material is based on systematic and spontaneous observations of twelve species of waders, made on the same days during the autumn migration in July–October 2010–2019. There is a significant positive correlation between the two methods for nine of twelve species. However, there is a large variation in the strength of the correlations, with the strongest correlation seen for Dunlin Calidris alpina. The Wood Sandpiper Tringa glareola, Green Sandpiper Tringa ochropus, and Little Stint Calidris minuta, on the other hand, show no significant correlations. This shows the difficulties in evaluating quantitative data of the wader occurrence at stopover areas such as Getterön. The variation in correlation between count methods between different species entails an uncertainty, which is probably due to low reliability in the spontaneous reporting. Thus, in the case of studies of staging waders based solely on spontaneous data, caution should be exercised.